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6 - A Depth-of-Field Myth

The Depth-of-field Zone
Is 1/3 in Front of the Subject,
And
2/3's Behind the Subject

There's a rule for depth-of-field that's set in stone:

The depth-of-field zone is 1/3 in front of the subject, and 2/3 behind the subject.

It's incorrect, however.

You'll encounter the rule everywhere.

For example, the myth appeared as fact in a prominent photography magazine in 2004.

When focusing on a deep subject, focus on a point about a third of the way into the picture to maximize depth of field, because the depth-of-field zone behind that point is about twice as deep as the depth-of-field zone in front of it.

Wrong!

Two Examples

Here are two examples from the DOFMaster Online Depth of Field Calculator.

They show how the rule is a myth.

In both examples, the camera is a 35mm film camera with a 50mm lens.

Example #1

At f/2.8, and focusing on a subject ten feet away from the camera, the depth-of-field zone is:

Zone In Front of the Subject Zone Behind the Subject
45% 55%

If the myth was true, the percentages should have been 33% and 66%.

Example #2

At f/16, and focusing on a subject 20 feet from camera, the depth-of-field zone is:

Zone In Front of the Subject Zone Behind the Subject
21% 79%

Again, if the myth was true, the percentages should have been 33% and 66%.

Don't use the myth.